Secret signaling system



Aug. 2i, i923. 1,465,368

W. J. SHACKELTON SECRET S IGNALING SYSTEM Filed Sept. 4, 1919 2Sheets-Sheet l o 3, Hg,

w 3:3/ ,mf |30 ./9 l s?V 3l I- I l 2 3/ :if L'eo'a" l 3 E la 40 L A @l7` f@ J f@ f f l f 4 ,schemi ao Aug. 21, 1923. '1,465,368

W. J. SHACKELTON SECRET SIGNALING SYSTEM Filed Sept. 4, 1919 2Sheets-Sheet 2 H, Hg. 4. ffy

//1 vena/4' W/V//m J Sh'ac/fp/ /0/1. l

y Affy WILLIAM ilE'ACKELTON,

F NEW YRE.

E' SCUTCH LAINS, NEW JERSEY, SSIGNGR TG XKIESTEBN ELECTRIC CVAN',INCRORATE,

Appcaziml i To @Z5 whom may; aan

Be it kn mi Limb L WIM AM J. Simyo TON, a citizen die Uniiod Etnica,YQSML ing ai Swich l ma, in tho county of iiiiioni State of i'eiv Jamey?iuveneei cefA win new usa'ui mprov'aii t5 in ociolim, of which i'olowing2. full, ii/daf, configs, :iii om@ descrip- 510i-,

This invention relates io signaling; systems und more paricuizu'iy o :alsystmn wherein iielgzapii summits are employed which are so :airmailiio; Hw" zmiot oe fieectefl bjr oxfiii "gnn wfrmvingf in uw moms out wzio' made omiii'iio in n tdephone recoin, V)sing coi'itinuousiy inmention inered to im and br:-

in Seix Cause ot x How fihi* fo ic-i-mptini the ici obtain im maximum'eceiver', ai@ asociated 0F NEVI Yfitl, N. YJ, i CORORATON' QL, LSB).Serial No. 321,692.

cuit emi'xuiyirw the inveuioii. the svf'itchs being in ibo properposition for ouiiing;

Fig, hows die cix'cnit of Figi; l in com (ition for fielding; i

Fig. .shows the @iroui oi' Fig1 ifi con@ dition for lxzcivii'ijg; Y

n climi ida'gnviii io fio usmi 'MLQMM. im :im 1^"ufiy varying'7 thecircuit Using in normal Condii Lion for riacoiving o cuil;

Fig. 5 Shows the, circuit of" Fig". A2; iu oonrii tion for caiiing5 andFig'. G shows: the fzixciiiof dition im? "da j o;- I

in alii. of iiio aiiowg, {fling-amis, iii@ p0rions of the (mitcontaining; iin@ vgfiixwlil are, shown in lift-iwf; iii iines. :imiiliopm'- tioiis conuning 10mi (fummo: :mi Shown in iii-:my dotcfilzi'ls.

efering; to figs. i, t2 and f3. the iin@ l() is adaped m be oonncfztef'm tho filter il, telegraph key l2., zeiistznw 15?, oattvriass 14 and L3,Cai'bon button 1G und meiver l? to ,ground at 15%, The filter 1lcou'ipxisilr; serics inducfmi-v; iff? and shunt nondensers QU. Thefi'wiiigs fbi and 552 ma): he owned whom signul;- .am no?, hing Sont inordm' io avoid v Switch :23 may be dosed to piov'iffe. i Himn. piiharound ocmdonsi'fi 255 when y0u-:fils is. 'Cow denser p'vovidinfa i1pi'zi 'for mai f-mx'vn if'iig. ii; volifi'equenf'is. The diapiii'ugniiof l,csivvi if?? is in cori'lzuf; wili tim 'milton und when switch ne.closwL (continuum 'iiifimiiois produce, simiim filmma- L' Tinpmpos ofthis;

'imi to 35 and 36 are open.

In the line 10 is placed the secondary 31 of transformer or inductioncoil 30, which may be of the Rumkorii1 type. The primary circuit of theinductionL coil comprises the primary 32, the. interruptor 53, condenser34, switch 35, and batteries 14 and 15. When the switch 35 is closed,calling currents of a suitable strength and frequency for producing aloud sound in a receiver at a distant station 'are sent out on line 10.'When a call is being sent switch 3S may be closed to short-circuit theapparatus betvveen secondary 31 and ground 18.

When it is desired to use the line for telephony, a transmitter 4() anda receiver 41 may be plugged in, the former being connected across theprimary 32 and the battery 14 and the receiver directly in series withthe grounded part of the line and with one 0i' tne condensers 20. Itwill be seen that the induction coil 30 serves as a transformer whentelephone messages are being sent, and that received telephonernessa'ges are not required to pass through inductances 19 of the filter11.

The operation of the circuit for secret telegraphy is as follows:

For sending a call, the switches are in the positions shown in l., thcinduction coii 30 serving,r to tranfginit 'the calling current. Switchserves a key for closing batteries 1li and 1.3 through the primary oiEthe induction coil. The normal position for receiving a oeil is .likethat shown in Fig. 1 except that the switches The received callingcurrents pass through one or more ot the condensers 2G `which are inseries with receiver 17 and produce u. loud sound in the receiver.

When sending telegraph messages the cir cuit is shown in 2. rthete'egraph key 12 is operated and sniali direct current impulsescorrespondingr to suitable signaling code, such as the Morse code, sentout through the filter 1l ontheline l0. The strengthiof the current maybe reeulated by resistance 13 and should be so :feeble that it cannot'be detected by most sensitive relays employed in teiegraphy. The distantstation, however, provided with means for chopping or varying the curiiets sov as to render them audibie in a telephone receiver. This vmeans issimiiar to the arrangement at the sending station, the opern ation ofwhich will now be descr sed.

The signal currents pass through button 16 at the-v sending stationshown in i?, and through a similar button Aat the ceiving station. Thesebuttons are continuously vibrated by the armatures of electromagnets225, 'and by reason of the chang ing resistance of the button continuousfluctuations orcurrent are set up. For most efficient operation, it hasbeen found that these fluctuations should be at a considerable higherfrequency than the frequency of the calling currents produced byinduction coii 30. The chopper at the distant station renders the signalcurrents audible in a receiver at that station and the chopper at thesending station renders them audible in the receiver 17,tlius'affordingthe Sending operator means tor determining Whethersignals are being properly transmitted or not. The filter 11 is providedto prevent the current fluctuations from passing out to the line Wherethey might be heardl by an unauthorized person.

The local circuit for the alternating component ot' the current isprovided by the condenser 28, one or morevoi condensers 20 and' theswitch 27. it will. be seen that, when sending, switch 27 is thrown tothe left, connectingr the condensers 20 from the line to ground andthereby putting them in proper position'to function as a part of theiilter. Switches 21 and v22. are, of course, closed and switch 23 isopened.

When receiving, switch 23 is closed and feeble direct current signalsfrom the distant station pass through the chopper button 16 and receiver17 rvhere they are made audible as above described. The flow of signalcurrent during reception is shown in heavy full lines in Fig. 3.

It will be seen that in the circuit, as in Fig. 2 or in Fig. 3, currentscan pass through the receiver 17 only when the telegraph key at the samestation or at a distant station is closed. There is thus no possibilityof sounds being,r produced in the receiver 17 when neither key isclosed' by reason ot' differences in ground potential between the tvvostations. Ground potentials oniy act in series with the set battery andact to increase or decrease the strength ot signals, but do not causetone during silent intervals.

Referring to Figs. 4.-, 5 and 6, the line 10 is connected through filter11 which is simi,-h iar lto fitte-'r11 and then to ground throughparallel paths, tine of which includes the telegraph ire-y 12 and theother of which includes receiver i7" and carbon button 16". Condenser4&5 and suY ch i8 are provided to torni a iocai circuit with. receiver17 and button 16 for alternating currents produced by the chopper, whichis similar to that shown in Fig. 1.' A local circuit for direct currentsthrough the receiver when transmitting comprises the switch 47 andresistance e6, which isemployedto equalize the line.

furnish the signaling currents. switch 50 is employed to *from theprimary circuit nipedance of this circuit with that o the- Leccese orinduction coil to the chopper circuit and telegraph key. The switch 51may be closed Vnentlv connected across the line, a battery Y ichpotentiometer 53 and switch 54 is employed to oppose any steadygroundpotentels which may ne found to exist.

own in Fig. .4, in the normal posithe circuit, calling currents pamrough to the first condenser 20, condenser r ver 1T and thence to groundhrou the shunt path comprising the witch- 5l, eil other switches being oen as When a call is to ce sent, switch 48 oecd es shown in Fig. 5 andswitch 50 thrown to close the rimary circuit of the induction coil witch5l is opened'. The secondary circuit for the calling currents will seento include the shuntl peth oe through switch 48.

The position of switches for sending or receiving messages is the suineand is shown in Fig. 6. switch being thrown to the upper position so asto operate the chopper hutten 2li. Switch e? is closed so that part o'the curr-cnt may pass through receiver 17 sending, for the purpose above'expisined.

le will he understood that both in the 'lorm shown in Fig. l and in Fig.4, the

switches may be arranged to be operated by a common turn button orhandle, but are shown seperatein the drawings merely for the purpose ofsimplifying the circuit diaems.

The invention is not limited to the specific forms shown and described,but is entitled to equivalents' within the scope of the appended claims.

What is claimed is:

l. combination,` a line, and a station comprising e Wave filter, atelegraph key, a

source of signaling current. continuously opera'ole means for pmducinpYiuctuations of current, and a. receiver, said elements beinr connectedinseries with each other, sai filter being interposed between said lineand the part of the circuit containing said continuously operable meansand said receiver.

2. In a signaling system, a receiver and means in series tlferewith forcontinuously varying the current therethrough, a line, means to reventsaid variations from passing to said line, a telegraph key at a dista-ntstation, a source of current, and connec tions so arranged that, on.i'e/ceiving, the line circuit is closed to direct current only whensaid distant key is closed.

3. A signaling system comprising a line, a filter, a telegraph key, areceiver, and means for connecting said receiver in series with said keyand for connecting said filter between said receiver and said line whenlsignals are being transmitted and means for chan ing the circuitconnections between said iter and said receiver when a call is to bcreceived.

4. A signaling system comprising` aline, a receiver, a filtercomprisingan inductance and a capacity, and means for connecting saidreceiver to said line et times so that' line currents flow to said,receiver principally through said inductancc and at other times -So thatline currents How' to said receiver' principally th rough. saidcapacity.

5. 1n a signaling 'sy-stem, a line, a filter connected thereto, meansproviding'at times a path in shunt to said line and to a path includingsaid Filter, means for continuously varying currents passing throughsaid iilter, a receiver in series with said means, and separate meansfor producing,r calling current and transmitting said calling current insaid shunt path.

n witness whereof l hereunto subscribe my name this 28th day of August,A. D.

WILLIAM J. l'l'ACKELTON

